Beirut, Lebanon — A tenuous truce in Syria has survived into its second full day of implementation and brought some welcome respite to the beleaguered country.

But there are strong doubts it can hold given the myriad competing interests swirling across the country and the deep hostility and lack of trust between the two main protagonists – the regime of President Bashar al-Assad and the armed opposition, which seeks to overthrow him.

Although the full details of the agreement, reached by the US and Russia in Geneva after prolonged negotiations, remain unclear, analysts say the deal appears weighted in favor of the Assad regime and its Russian and Iranian allies rather than the Syrian opposition. Hours ahead of the cease-fire agreement coming into effect Monday evening, Mr. Assad repeated his vow of defeating rebel forces and restoring the whole country to state control.

The deal implicitly recognizes US acceptance of Russia’s role as a key political and military actor in Syria, an endorsement Moscow has long sought. Furthermore, Washington has evolved from a critic of Russia’s year-old intervention in Syria to a battlefield ally of Moscow as they prepare to launch airstrikes against extremist groups.

As for the rebel groups, the agreement calls on the mainstream factions to move away geographically from Jabhat Fateh ash-Sham, formerly known as Al Qaeda-affiliated Jabhat al-Nusra, even though the extremist group is one of the most potent anti-Assad forces.

And if one side or the other breaches the agreement, analysts say it is doubtful that the US or Russia has either the leverage or the political will to restore the truce. Little wonder, then, that there is such widespread pessimism about the durability of the cease-fire arrangement.

Humanitarian aid delayed

“I think the most important [threat to the agreement] is that the Syrian government has not relinquished its goal of recapturing all Syria in the medium- to long-term,” says Robert Ford, a senior fellow at the Middle East Institute in Washington and former ambassador to Damascus. “So it’s hard to see how a cease-fire can last when the Syrian government almost certainly will be testing the edge of the envelope to see how far it can go, one village here, a small street there, without drawing massive Russian condemnation.”

The cease-fire agreement was reached early Saturday between Secretary of State John Kerry and his Russian counterpart, Sergey Lavrov, in Geneva. The deal, the latest in a series of attempts to halt the fighting, calls in part for the cease-fire to be renewed every 48 hours and places a priority on delivering humanitarian aid to civilian areas.

The arrangement came into effect Monday at sundown, but no aid has been delivered as yet due to the frailty of the security situation on the ground. The initial focus of the aid deliveries is Aleppo, Syria’s former economic hub in the north of the country, which has been decimated by five years of war. Around 20 trucks loaded with food and flour and destined for Aleppo were stuck at the Turkish border with Syria Wednesday over squabbles between the Syrian regime and rebel groups over how to deliver the aid through multiple checkpoints.

George Sabra, a Syrian opposition politician, accused the Syrian government of attempting to control the flow of aid to Aleppo and other areas, voicing pessimism that the cease-fire will last.

“There is no great confidence that this truce can last longer than the previous one,” he told Reuters, referring to a temporary lull earlier in the year.

Protection for civilians

Despite the cease-fire’s gloomy prospects, a key consideration toward pushing the diplomatic process forward would be to remove Syria’s civilian population from the firing line, says Fred Hof, director of the Rafik Hariri Center for the Middle East at the Atlantic Council in Washington.

“Unless civilians are taken off the bull's-eye, nothing good can happen in the political-diplomatic sphere,” says Mr. Hof, also a former State Department official working on transition in Syria. “For five years the Assad regime – with Russian and Iranian help – has sought to survive politically through collective punishment and mass homicide. If this strategy can be terminated and if other practitioners of mass terror,” the Islamic State (IS) and Jabhat Fateh ash-Sham “can be neutralized, progress toward a political solution is possible.”

Still, the clause that states mainstream rebel factions must disassociate from extremist groups, namely IS and Jabhat Fateh ash-Sham, could alone lead to the unraveling of the agreement. While IS is as much an enemy of Syrian opposition forces as the Assad regime, the powerful Jabhat Fateh ash-Sham is a crucial tactical ally for many groups and has a strong influence in parts of northern Syria, including Aleppo where it is interlocked on the front lines with other factions.

“It’s hard to get the opposition to go along with something that they suspect and know that the regime will take advantage of to find a military solution to the conflict,” says Andrew Tabler, a Syria expert at the Washington Institute for Near East Peace.

If the rebel forces move away from Jabhat Fateh ash-Sham positions, it will expose the extremists to attack from Russian, Syrian, and American aircraft.

“The Americans would be acting in that instance as Assad’s air force,” says Ambassador Ford of the Middle East Institute.

Split in rebel ranks

From the rebel perspective, therefore, the truce agreement splits opposition ranks, could lead to the decimation of a powerful ally by Syrian, US, and Russian air power, and, in turn, could leave the more moderate factions vulnerable to future offensives by the Syrian Army and its allies.

“What guarantees does the armed opposition have that would make it believe that the risks it is being asked to take will result in something other than its own destruction?” asks Hof of the Atlantic Council.

For its part, Jabhat Fateh ash-Sham may not simply wait for its allies to depart and then be bombed from the air. It could take matters into its own hands by launching its own offensive against the Syrian Army in a bid to collapse the cease-fire and ensure that its rebel comrades remain by their side.

Apart from the some limited military support for Syrian rebel groups, the US government has sought to avoid being sucked into the Syria conflict. But if the cease-fire falters and begins to come apart, Washington has little leverage over so many players and competing interests to bring the deal back on track, thus perpetuating a conflict that has killed more than 300,000 people and torn the country apart.

“Has John Kerry been empowered to tell Sergey Lavrov that the US will use military means – far short of invasion and occupation – to exact a painful price of the Assad regime if attacks on nationalist rebels and civilian population centers continue or resume? I doubt it,” says Hof. “And without a real ‘Plan B’ ready for execution, it is not clear how and why the Assad regime, Russia, or Iran would fear the consequences of double-crossing Washington.”